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9
CHAPTER 2: HMS-10 LOUDSPEAKER
HMS-10 INPUT CONNECTOR
The HMS-10 receives DC power and balanced audio from
its Phoenix 5-pin male connector on the top panel. The con-
nector’s five pins include two pins for DC power (negative
and positive) and three pins for balanced audio (shield, neg-
ative, and positive). These pins are clearly labeled on the
HMS-10 top panel. The connector accepts conductors up to
12 AWG (American Wire Gauge) or 2.5 mm
2
. To function
properly, the HMS-10 requires an external 48 V DC power
supply.
A single composite cable (such as Belden 1502 or equiva-
lent) can be used to route both DC power and balanced
audio to the HMS-10 loudspeaker.
Each HMS-10 loudspeaker comes with one Phoenix 5-pin
female cable connector for making loudspeaker cables. For
information on HMS-10 cable requirements, see “HMS-10
Current Draw and Cable Requirements” on page 9. For
information on cables and cable accessories available from
Meyer Sound, see Appendix A, “HMS-10 Accessories.” For
information on cable assembly, see Appendix B, “HMS-10
Cable Assembly.”
CAUTION: When wiring HMS-10 loudspeaker
cables, it is extremely important that each pin
be wired correctly. Make sure the 48 V DC from the
external power supply is wired directly (and only) to
the 48 V DC pins on the HMS-10 loudspeaker con-
nector, and that the polarity is observed (negative to
negative, positive to positive) to avoid damage to the
loudspeaker. In addition, make sure that audio pins
are wired correctly; polarity reversals for audio signals
affect system performance.
HMS-10 CURRENT DRAW AND CABLE
REQUIREMENTS
Each HMS-10 loudspeaker draws a maximum current of
3.31 A rms and 3.45 A peak from its external 48 V DC power
supply. The current draw for the HMS-10 is dynamic and
fluctuates as operating levels change. The cabling between
the HMS-10 and its external power supply adds resistance
and hence causes a voltage drop at the loudspeaker.
Because lower voltages compromise peak SPL, and in
some cases frequency response, cable resistance should be
minimized.
NOTE: For long cable runs, you can use a large
cable gauge for DC power and a separate bal-
anced audio cable for audio.
Cable Lengths and Cable Gauges for HMS-10
Loudspeakers
Cable lengths of up to 150 feet between the HMS-10 and its
external power are supported with only 1 dB of peak SPL
loss when using 18 AWG wire. Longer cable lengths are
possible with heavier wire gauges (see Table 1 and Table 2).
NOTE: The total cable resistance between the
HMS-10 and its external power supply should
not exceed 2 ohms.
HMS-10 Input Connector
!
Table 1: HMS-10 Loudspeaker Cable Lengths (AWG)
Cable Gauge Resistance
(:/ft)
Approximate
Max. Length
12 AWG 0.0016 600 ft
14 AWG 0.00253 375 ft
16 AWG 0.00402 237 ft
18 AWG 0.00636 150 ft
20 AWG 0.01008 87 ft
Table 2: HMS-10 Loudspeake r Cable Lengths (European)
Cable Gauge Resistance
(:/m)
Approximate
Max. Length
2.50 mm
2
0.0052 157 m
1.50 mm
2
0.01076 87 m
1.00 mm
2
0.02087 45 m
0.75 mm
2
0.03307 27 m